Support triage example

A small Mix application that routes inbound support messages with one TypeSafeAPI.evaluate/4 call, and whose entire test suite runs offline: no API key, no network, no recorded fixtures.

That is the point of the example. Most AI client libraries leave you choosing between hitting a paid API from CI, maintaining a cassette directory, or mocking at a layer so low that the test no longer exercises your decoding. TypeSafeAPI.Test stubs by question id and builds the same structs a real response decodes into, so the code under test is the code that runs in production.

What it does

SupportTriage.triage/2 asks three questions about one message, in a single request:

Then it gates on confidence with TypeSafeAPI.Answer.gate/2 and decides:

• {:escalate, dept} — blocked, or angry enough to need a person today.
• {:queue, dept} — routed to a team's normal queue.
• {:needs_human_review, reasons} — at least one answer did not clear the confidence bar, so the app refuses to guess. Each reason carries the answer and whether it was borderline (:review) or close to a coin flip (:escalate), which is something a classifier returning a bare label cannot tell you.

SupportTriage.triage_many/3 does the same for a list of messages with TypeSafeAPI.evaluate_many/4, which validates and encodes the question set once into a TypeSafeAPI.SystemOne.Prepared struct and reuses it for every message. Outcomes come back in input order, and one failed message does not sink the batch.

Run the tests offline

mix deps.get
mix test

No TYPESAFE_API_KEY needed, and none is used even if one is set: every test builds its client with TypeSafeAPI.Test.client/1. The suite covers the escalation path, the queue path, the low-confidence path, batch ordering, partial batch failure, and a 429 surfacing as {:error, %TypeSafeAPI.Error{type: :rate_limited}}.

Two stubbing styles appear in test/support_triage_test.exs:

• TypeSafeAPI.Test.stub/2 when one set of answers covers the test.
• A plain Req.Test.stub/2 function that answers differently per state, for the batch tests. It shows the wire shape TypeSafeAPI.Test builds for you.

Run the demo

mix support_triage.demo

Triages a handful of sample messages and prints each decision. With TYPESAFE_API_KEY set it calls the real API; without one it falls back to the same stubs the tests use. The first line of output says which mode it ran in.

Layout

lib/support_triage.ex            questions, gating, routing
lib/support_triage/demo.ex       sample messages and their offline stubs
lib/mix/tasks/support_triage.demo.ex
test/support_triage_test.exs     the whole suite, offline

The library is a path dependency ({:typesafe_api, path: "../.."}), so the example always builds against the working tree rather than a published release.